Push switch, especially for ac use

ABSTRACT

A push switch in which there is step-by-step advancement of a rotary cam. The cam configuration acts on a movable contact to effect a fast-make, slow-break action. Cooperating ratchets on the cam and switch body index the cam and have a shape that builds in a &#39;&#39;&#39;&#39;time tolerance&#39;&#39;&#39;&#39; such that the indexing of the cam need not coincide perfectly with the drop-off of the movable contact to the &#39;&#39;&#39;&#39;make&#39;&#39;&#39;&#39; position. A coil spring incorporated in a motion translating mechanism between the button and cam is placed under added compression when the indexing ratchets approach coincidence, accelerating the &#39;&#39;&#39;&#39;fast make.

Unwed States Fattent 1151 3,646,297 Anthony Feb. 29, 1972 [54] PUSH SWITCH, ESPECHALLY FOR AC 2,096,386 10/1937 Taubner 200/156 x USE 3,497,643 2 1970 Heath ..200/153 LB x [72] Inventor: Walter 111. Anthony, Levittown, Pa. primary v Truhe [73] Assignee: Circle F Industries hm Assistant Examiner-Gale R. Peterson Att0rneySperry and Zoda 1221 Filed: Ju1y 16,1970

21 App1.No.: 55,309

[57] ABSTRACT A push switch in which there is step-by-step advancement ofa rotary cam. The cam configuration acts on a movable contact to effect a fast-make, slow-break action. Cooperating ratchets on the cam and switch body index the cam and have a shape that builds in a time tolerance such that the indexing of the cam need not coincide perfectly with the drop-off of the movable contact to the make position. A coil spring incorporated in a motion translating mechanism betweenthe button and cam is placed under added compression when the indexing ratchets approach coincidence, accelerating the "fast make.

2 Claims, 12 Drawing Figures J g Z Patented Feb. 29, 1972 3,646,297

3 Sheets-Sheet z I IJVEHTOFL \NAL'ren. HAM-mow ATTOrLHEYS Patented Feb. 29, 1972 3,646,297

3 Sheets-Sheet 5 mveu'ron. Wan-em H. Amnouv BY AfMNI PUSH SWITCH, ESPECIALLY FOR AC USE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to the electrical switch art, especially switches of the fast-make, slow-break type designed especially for alternating current use as control or so-called canopy" switches used to control the operation of vacuum cleaners, fans, and other household appliances. In this art, switches include handles of various types, that is, rotary, toggle-acting, etc. The switch comprising the present invention is of the push type, in which a single-pole switch is turned on and off by successive depressions of a pushbutton, that is, by a push-on, pushoff operating sequence.

2. Description of the Prior Art The present invention incorporates a motion-translating mechanism between a pushbutton and a rotary, contact-biasing cam. The prior art abounds with switches of this general type. However, there has been an increasing demand for more and more powerful switches. By this is meant switches capable of controlling relatively heavy electrical loads. This problem has arisen by reason of the fact that household appliances are becoming more and more powerful as regards the electrical components thereof, including the electric motors used in household tools, vacuum cleaners, and the like. Yet, despite the fact that such appliances are becoming characterized, more and more, by increases in the electrical ratings thereof, the wiring device industry has still been required to design control switches for such appliances that are no larger, and hopefully no more expensive, than they have been accustomed to provide in past years.

This requirement for higher-rated control switches of a compactness and cost approximating those previously made, has obviously produced many problems in wiring device design. Switches of this type must undergo extremely difficult tests to be listed by Underwriters Laboratories. The original equipment manufacturers purchasing the switches for use as components in the appliances which they make also have established stringent requirements. All this has made it exceedingly difficult to provide a switch design in which the make and break of the contacts is effected in such manner as to permit the switch to meet the noted requirements while operating under heavy load.

The prior art includes, typically, such patents as the following:

Ely l,l62,735

Bryant et al. 2,l95,237

Taubner 2,291,993

Pomcrantz 2,466,910

Schneider 2,798,907

Lewis et al. 2,965,737

Bcnander et al.

Schmicr et a]. 3,973,933

SUMMARY OF THE INVENTION Summarized briefly, the invention incorporates a pushbutton, a motion-translating mechanism driven by depression of the pushbutton, and a rotary cam turned by said mechanism, with the cam being indexed through the provision of cooperating ratchets on the cam and on the switch body. The circumference of the cam is provided with uniformly, angularly spaced cam lobes, controlling deflection of a movable switch contact between make and break positions thereof. The ratchets and the configuration of the cam periphery are such as to build in a time tolerance" adapted to eliminate the need for precision formation and alignment of the indexing ratchet means, cam periphery, and movable contact. In this way, assurance of the absolutely essential fast-make is obtained, and an adaptability is built in for long, efficient switch life even under heavy loads, while at the same time permitting manufacture of the switch at a low cost.

The invention, summarized further, incorporates a design of the indexing ratchet means such as to give an added impetus or acceleration to the fast-make action of the movable contact, at the moment when the movable contact drops off the cam lobe to its make position. Building in this adaptability for accelerating the make of the contacts beyond that speed of make which is normally characteristic of switches of this type, causes the switch to operate under heavier-than-normal loads, and under test procedures that have produced switch failures in the past.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view through a switch according to the present invention;

FIG. 2 is a view substantially on line 2-2 of FIG. I;

FIG. 3 is a longitudinal sectional view through the operating mechanism substantially on line 33 of FIG. 2;

FIG. 4 is a transverse sectional view through said mechanism substantially on line 4-4 of FIG. 3;

FIG. 5 is a bottom plan view of the rotary cam, per se;

FIG. 6 is a development of the bottom ratchet of the cam;

FIG. 7 is a sectional view diametrically through the cam, taken substantially on line 77 of FIG. 5;

FIG. 8 is a fragmentary plan view of the switch body per se, showing the indexing ratchet thereof;

FIG. 9 is a development of the ratchet of the switch body;

FIG. 10 is a fragmentary sectional view of the switch on the same cutting plane of FIG. 1, with the rotary cam approaching one of its indexed positions;

FIG. 11 is a development of the cooperating indexing ratchets of the cam and body, as they appear when the cam is in the FIG. 10 position; and

FIG. 12 is a fragmentary view similar to FIG. 2, with the cam and movable contact approaching the make position thereof, the cam being in the same position as shown in FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT A switch constructed according to the present invention includes a relatively flat switch body 10 formed of a suitable electrically insulative material, for example a thermosetting phenolic resin, urea, or the like. In the illustrated example, which would be typical, the switch is roughly oval in plan, with an upwardly opening recess containing the switch mechanism. The switch might be made with any suitable type of termination according to the requirements of the customer, and by way of example, the switch body is illustrated as including wire holes l2, 14 opening through the bottom of the switch body, at opposite sides of a centrally disposed boss 16 formed on the bottom wall of the body, and formed with a bearing recess 18 opening into the switch cavity or interior 20.

Concentric with and extending completely about the bearing recess 18 is an indexing ratchet 22 molded into the top surface of the boss 16, comprising a series of like, uniformly angularly spaced ratchet teeth shown to particular advantage in FIGS. 8, 9, and I1.

Mounted in the switch cavity 20 is a stationary contact 24 which in the illustrated example of right-angular form. A wire lead 25 is welded or otherwise secured to said contact, extending through the wire hole 14. As is customary in the wiring device art, the contact 24 is held in place within the switch body through the provision of suitable molded-in shoulders, abutments, or guideways, and in the present instance a depression 26 is formed in the bottom wall of the switch body, shaped to receive and hold stationary the contact 24.

Provided upon one end of contacts 24 is a contact button or head 28.

An elongated movable contact 3% is welded to a wire lead 32, and has a proximal end portion anchored in a depression 32 formed in the bottom wall of the switch body. In the illustrated example, a removable spacer 33 aids in proper positioning of the movable contact.

The distal end portion of the movable contact is in the form of an elongated spring arm 34, having at its extremity a contact button 36, and having intermediate its ends a lanced-out cam projection 38. Projection 38 is engageable by a rotary cam 40 which may advantageously be molded of the same material as the switch body. Cam 40 includes (see FIG. 1) a stub axle 42 rotatably seating in bearing recess 18. Molded in the bottom surface of the cam, about the stub 42, is a bottom ratchet 44 the development of which is shown to particular advantage in FIG. 6. As noted from the figure of the drawing, each tooth of the ratchet has a short, inclined drop-off slope 45 inclined oppositely to an elongated, gradually sloped incline 47. Contiguous to the drop-off slope 45 is a vertical abutment 49,

In the periphery of the cam, cam recesses 48 alternate with lobes 50, adapted to engage the projection 38 of the movable contact for the purpose of biasing the movable contact away from the stationary contact.

Formed in the upper surface of the cam 40 is an upper ratchet 52. At this point, it may be noted that the terms upper" and bottom" refer to the orientation of the described components as they appear in the drawing, in particular FIG. 1. Obviously, the switch may be mounted in any of various positions when in actual use controlling an electrical ap pliance, and may even be used in a position completely inverted from that illustrated in FIG. 1.

The upper ratchet 52 comprises uniformly, angularly spaced teeth each of which has an inclined cam surface 53 and a vertical abutment surface or stop 55. The upper ratchet extends about an upwardly opening recess 57 formed in the cam.

The switch includes an insulator 54 the periphery of which registers with the periphery of the switch body. Insulator 54 is stamped from electrical fiber or other suitable electrically in sulative material, and covers the switch cavity. Centrally formed in the insulator 54 is an opening 56.

The insulator is interposed between the switch body and a metal cover 58. The body, insulator 54, and cover 58 have registering apertures receiving rivets 59 or other fastening means for permanently assembling the switch components.

The cover includes a flat plate in face to face contact with the insulator, integral with an upwardly extending nipple 60. There is thus provided a housing generally designated 61, comprised of the switch body ll), insulator 3, the metal cover 58.

Nipple 60 has a bore 62 which as shown in FIG. 4 is of circular cross section, opening at the upper end of the nipple through a noncircular aperture 63 in which is slidable a push button or handle 64 having an enlarged lower end 65 (see FIG. 3). As a result, when the push button is depressed, it is held against rotation by reason of the fact that diametrically opposed flat surfaces thereon extend along correspondingly flattened, diametrically opposite edges of the aperture 63.

A motion-translating mechanism generally designated 67 (see FIG. 1) includes a spiral 68, extending within a compression coil spring 70 interposed between a spiral guide 66 seated within the enlarged lower end (see FIG. 3) 65 of the pushbutton. The compression coil spring thus would normally tend to urge the pushbutton upwardly to its normal, extended position shown in FIG. 1. Limiting the upward or outward movement of the pushbutton are shoulders 72 (see F108. 3 and 4) defined by the inwardly extending flat edge portions of aperture 63. These limit the button against movement under the pressure of the coil spring beyond the normal extended position of the button.

Formed on the lower end portion of the spiral are laterally outwardly extending wings 72, the bottom edges of which are in engagement with the upper ratchet 52 of the rotary cam. Below the wings. the spiral extends into the central recess 57 of the cam.

OPERATION In use, the components would appear, in the on or make position of the switch, in the position shown in FIGS. 1 and 2. At this time, the indexing ratchet means cooperating between the cam and body, designated at 22, 44 respectively, are fully interengaged or mated. The cam may in these circumstances be considered as being in a lower position.

At this time, the movable switch contact is in the FIG. 2 position, with the contact buttons 28, 36 in engagement and the projection 38 registered with a cam recess 48 of the cam 40. Cam 4G is completely out of contact with the movable switch arm. It may be noted, in fact, that the distance between the projection 38 and the adjacent surface of the cam recess 48 is quite substantial, so that the cam might even be turned a few degrees from its FIG. 2 position, without affecting the position of the movable contact 34. This builds in a tolerance which permits manufacture of the switch at a relatively low cost.

If, now, the switch button is depressed, the spiral is caused to turn, due to the provision of guide slot 74 formed in the spiral guide 66. This particular motion-translating mechanism, it may be noted, in and of itself is well known. In any event, as the push button is depressed, the spiral turns and coil spring 70 goes under added compression. The lower end of the coil spring, it may be noted, bears against the top surfaces of the wings 72. Pressure is accordingly transmitted through the wings to the cam 40, tending to urge the cam downwardly in FIG. 1.

Wings 72 bear against the vertical abutments 55 of the top ratchet 52 of the cam, and accordingly the spiral and cam rotate together. This causes the cam to ride upwardly on the ratchet 44 of the switch body, to the position shown in FIG. 10 and also in FIG. 11.

This also causes the cam to bias the movable switch contact arm 34 away from the stationary contact, and it will be noted that the particular shape of the cam lobes is such as to assure a desirably slow break found especially important in alternating current operation. Ultimately, the cam is fully indexed to its next position, in which the movable contact arm is in engage ment with one of the cam lobes 50, in spaced relation to the stationary contact.

On the next depression of the push button, the cam is indexed to its next following position. Again, the bottom ratchet of the cam rides up on the ratchet of the body. As the cam moves to the FIG. 12 position thereof, the cam bottom ratchet teeth engage the drop-off slopes of the ratchet teeth of the body, and this causes the cam to be advanced still further to its fully indexed position, which will now be a make position with the movable contact arm once again in the position thereof shown in FIG. 2.

It is very important to note that the construction is such that with the drop-off slopes, a time tolerance is built into the switch. In a commercial embodiment, a 6 leeway is permitted for a fast make, that is, there can be a 6 variance between the indexing ratchet means and the peripheral cam surface of the rotor. If this were not permitted, the drop-off of the contact arm 3% would have to be perfectly timed to coincide with the indexing means provided between the cam and body provided at 22, 44 respectively. By reason of the construction illustrated and described, the indexing means 22, 44 cooperating between the cam and body may be offset angularly from the drop-off slopes of the cam lobes 50, to the extent of a predetermined number of degrees, for example 6 degrees, thus building in the time tolerancementioned above. The need for precision formation and relative positioning of the movable contact, the periphery of the cam, and the indexing means for the cam is thus eliminated, and there is no danger of the movable contact hanging" when the cam is fully indexed, this being a malfunction that would destroy the fast-make and hence would cause serious arcing with consequent rapid destruction of the switch.

Iclaim:

i. A switch comprising:

a. a housing having a bottom wall;

. contacts within the housing one of which is spring-biased toward the other;

, a cam rotatable in the housing and formed with a peripheral cam surface against which said one contact bears, the cam having a bottom surface facing said bottom wall;

. a push button mounted in the housing for depression and return motion, in line with the cam axis;

. a coil spring coaxial with and compressed between the means extending between the push button and cam for translating depression of the pushbutton into rotary motion of the cam;

. an indexing ratchet formed in the housing concentrically with the cam and projecting upwardly toward the cam from said bottom wall; and

h. a ratchet on the bottom surface of the cam mating with and projecting downwardly toward the first ratchet, the cam when rotated being biased axially by the mating ratchets toward the pushbutton to add to the compressive force of the spring and thereby build up said force to the maximum extent as the cam indexes to each of successively following, angular positions relative to the contacts.

2. A switch as in claim 1 wherein at least one of said first and second ratchets includes teeth having at one end steep end walls, said teeth having long inclines and having short drop-off slopes adjacent said end walls inclined oppositely to said long inclines, said slopes being angularly spaced about the axis of rotation of the cam at locations such as to assure indexing of the cam fully to said next following position when the cam is approaching said position and is within a toleranced, predetermined angular distance thereof.

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1. A switch comprising: a. a housing having a bottom wall; b. contacts within the housing one of which is spring-biased toward the other; c. a cam rotatable in the housing and formed with a peripheral cam surface against which said one contact bears, the cam having a bottom surface facing said bottom wall; d. a push button mounted in the housing for depression and return motion, in line with the cam axis; e. a coil spring coaxial with and compressed between the push button and cam, the button being depressible against the compressive force of the spring and returnable by the expansion of the spring along said axis; f. means extending between the push button and cam for translating depression of the pushbutton into rotary motion of the cam; g. an indexing ratchet formed in the housing concentrically with the cam and projecting upwardly toward the cam from said bottom wall; and h. a ratchet on the bottom surface of the cam mating with and projecting downwardly toward the first ratchet, the cam when rotated being biased axially by the mating ratchets toward the pushbutton to add to the compressive force of the spring and thereby build up said force to the maximum extent as the cam indexes to each of successively following, angular positions relative to the contacts.
 2. A switch as in claim 1 wherein at least one of said first and second ratchets includes teeth having at one end steep end walls, said teeth having long inclines and having short drop-off slopes adjacent said end walls inclined oppositely to said long inclines, said slopes being angularly spaced about the axis of rotation of the cam at locations such as to assure indexing of the cam fully to said next following position when the cam is approaching said position and is within a toleranced, predetermined angular distance thereof. 